(a) Technical Field
The present invention relates to a method of manufacturing an inner panel of a vehicle tailgate (hereafter, inner panel), and more particularly, to a method of manufacturing an inner panel of a vehicle tailgate designed to reduce the manufacturing time and cost by simultaneously forming a reinforcing member and an inner panel.
(b) Background Art
Sport Utility Vehicles (SUVs) or Recreational Vehicles (RVs) are equipped with a tailgate at the back of the vehicle to increase of the interior space and facilitate easy loading of cargo into the vehicle.
The tailgate is pivotally connected to the back of the vehicles to open and close. Therefore, a reinforcing member for enhancing rigidity is mounted on the tailgate to prevent deformation of the tailgate due to repeated opening and closing motions and to protect the vehicle in a rear collision. The reinforcing member is disposed between an inner panel and an outer panel of the tailgate, in a plate shape with a predetermined size and shape, and generally welded to the inner panel, as shown in FIG. 1.
Thus, according to the methods of manufacturing inner panels of the related art, as shown in FIG. 2, an inner panel 1a and partial reinforcing members 2a, 3a, 4a, 5a, and 6a are manufactured separately and then welded together. In other words, a total of six blanks of 1, 2, 3, 4, 5, and 6 are separately manufactured by the reinforcing members 2a, 3a, 4a, 5a, and 6a and the inner panel 1a, and then seated and welded on a jig for assembly.
Moreover, to manufacture the partial reinforcing members 2a, 3a, 4a, 5a, and 6a separately from the inner panel 1a, several steps are necessary including forming (or drawing) the parts with a press having a forming mold, trimming to cut off unnecessary parts (e.g., scraps) to create the finished product using a trimming mold (e.g., cutting mold), piercing the product to make a bore, and flanging to make additional shapes for welding. In other words, the inner panel and the reinforcing members are produced by forming, cutting, boring, and bending the blanks.
In these processes, the forming is a process that machines the blanks 1, 2, 3, 4, 5, and 6 according to the product design data and is the most important process determining the quality of the finished product.
As shown in FIG. 3, the apparatus for the forming process is equipped with a mold composed of a lower mold 20 conforming to the shape of the bottom of the inner panel or the reinforcing members (to be produced) and an upper mold 10 conforming to the shape of the top of the inner panel or the reinforcing members (to be produced). A blank is placed between the upper mold 10 and the lower mold 20, with the upper mold 10 open (e.g., raised), and as the upper mold 10 closes (e.g., lowers toward the lower mold) and presses the blank with a predetermined pressure, the blank is formed according to the shape of the inner panel or the reinforcing member.
Further, the formed blank is removed when the upper mold 10 is raised. The removed blank is trimmed, pierced, and flanged, as described above, and then assembled and welded with other parts, thereby manufacturing one finished inner panel.
The description provided above as a related art of the present invention is just for helping understanding the background of the present invention and should not be construed as being included in the related art known by those skilled in the art.